Gas turbine engines are known and include a compressor which compresses a gas and delivers it into a combustion chamber. The compressed air is mixed with fuel and combusted, and products of this combustion pass downstream over turbine rotors.
The turbine rotors typically carry blades having an airfoil. In addition, static vanes are positioned adjacent to the blades to direct the flow of the products of combustion at the blades. Both the blades and the vanes are exposed to very high temperatures, and thus cooling schemes are known for providing cooling air to the airfoils of the blades and vanes.
Cooling circuits are formed within the airfoil body to circulate cooling air. One type of cooling circuit is a serpentine channel. In a serpentine channel, air flows serially through a plurality of paths, and in opposed directions. Thus, air may initially flow in a first path from a platform of a turbine blade outwardly through the airfoil and reach a position adjacent an end of the airfoil. The flow is then returned in a second path, back in an opposed direction toward the platform. Typically, the flow is again reversed back away from the platform in a third path.
The assignee of the present invention has developed a serpentine channel combined with cooling circuits that are embedded into the wall of an airfoil, which have been called microcircuits. Example microcircuits are disclosed in U.S. Pat. No. 6,896,487, entitled “Microcircuit Airfoil Main Body,” and which issued on May 24, 2005.
It is known to provide a turbine blade having microcircuit cooling adjacent the entire length of both a suction side and a pressure side.